Cisco Catalyst 4000 Series Switches Dynamic ACL Bypass VulnerabilityCisco Security AdvisoryEmergency Support:
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More information can be found in Cisco Security Vulnerability Policy available at http://www.cisco.com/web/about/security/psirt/security_vulnerability_policy.htmlcisco-sa-20170906-catFinal1.01.02017-09-06T16:32:52Initial public release.2017-09-06T16:00:002017-09-06T16:32:52TVCEA vulnerability in the dynamic access control list (ACL) feature of Cisco IOS XE Software running on Cisco Catalyst 4000 Series Switches could allow an unauthenticated, adjacent attacker to cause dynamic ACL assignment to fail and the port to fail open. This could allow the attacker to pass traffic to the default VLAN of the affected port.
The vulnerability is due to an uncaught error condition that may occur during the reassignment of the auth-default-ACL dynamic ACL to a switch port after 802.1x authentication fails. A successful exploit of this issue could allow a physically adjacent attacker to bypass 802.1x authentication and cause the affected port to fail open, allowing the attacker to pass traffic to the default VLAN of the affected switch port.
There are workarounds that address this vulnerability.
This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170906-cat ["https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170906-cat"]This vulnerability affects Cisco IOS XE Software running on Cisco Catalyst 4000 Series Switches. For information about affected software releases, consult the Cisco bug ID(s) at the top of this advisory.No other Cisco products are currently known to be affected by this vulnerability.Administrators are advised to apply a port-specific ACL on all dynamic ACL access ports to act as a default if dynamic ACL assignment fails.For information about fixed software releases, consult the Cisco bug ID(s) at the top of this advisory.
When considering software upgrades, customers are advised to regularly consult the advisories for Cisco products, which are available from the Cisco Security Advisories and Alerts page ["https://www.cisco.com/go/psirt"], to determine exposure and a complete upgrade solution.
In all cases, customers should ensure that the devices to be upgraded contain sufficient memory and confirm that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, customers are advised to contact the Cisco Technical Assistance Center (TAC) or their contracted maintenance providers.To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy ["http://www.cisco.com/web/about/security/psirt/security_vulnerability_policy.html"]. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.This vulnerability was found during the resolution of a support case.THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE INFORMATION ON THE DOCUMENT OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS DOCUMENT AT ANY TIME.
A standalone copy or paraphrase of the text of this document that omits the distribution URL is an uncontrolled copy and may lack important information or contain factual errors. The information in this document is intended for end users of Cisco products.https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170906-catCisco Catalyst 4000 Series Switches Dynamic ACL Bypass VulnerabilityCisco IOS XE Software Cisco Catalyst 4000 Series Switches Dynamic ACL Bypass VulnerabilityCSCvc72751A vulnerability in the dynamic access control list (ACL) feature of Cisco IOS XE Software running on Cisco Catalyst 4000 Series Switches could allow an unauthenticated, adjacent attacker to cause dynamic ACL assignment to fail and the port to fail open. This could allow the attacker to pass traffic to the default VLAN of the affected port.
The vulnerability is due to an uncaught error condition that may occur during the reassignment of the auth-default-ACL dynamic ACL to a switch port after 802.1x authentication fails. A successful exploit of this issue could allow a physically adjacent attacker to bypass 802.1x authentication and cause the affected port to fail open, allowing the attacker to pass traffic to the default VLAN of the affected switch port.CSCvc72751CVE-2017-12213CVRFPID-930364.7CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:NAdministrators are advised to apply a port-specific ACL on all dynamic ACL access ports to act as a default if dynamic ACL assignment fails.https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170906-catCisco Catalyst 4000 Series Switches Dynamic ACL Bypass Vulnerability